FAIR VALUE MEASUREMENTS - Fair Value Measurement Inputs and Valuation Techniques (Details) $ in Millions		Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 78,099	$ 75,741
Equity securities		1,087	1,091
Assets, fair value		86,105	82,924
Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		1,719	1,778
Equity securities		221	209
Assets, fair value		1,940	1,987
Valuation, Cost Approach | Level 3 | Private Financials
Fair Value Measurement Inputs and Valuation Techniques
Equity securities		221	209
Municipalities
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		2,416	2,320
Municipalities | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		0	0
Mortgage- and asset-backed securities
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		2,567	2,146
Mortgage- and asset-backed securities | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		418	343
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 418	$ 343
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Lower Limit | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[1]	82.69	97.38
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Upper Limit | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[1]	107.62	106.71
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Weighted Average | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[1]	100.39	102.98
Public utilities
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 7,933	$ 7,666
Public utilities | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		350	497
Public utilities | Discounted cash flow technique | Level 3 | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 350	$ 497
Public utilities | Discounted cash flow technique | Level 3 | Lower Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0170	0.0128
Public utilities | Discounted cash flow technique | Level 3 | Upper Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0268	0.0286
Public utilities | Discounted cash flow technique | Level 3 | Weighted Average | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0206	0.0192
Sovereign and supranational
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 728	$ 834
Sovereign and supranational | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		37	37
Sovereign and supranational | Consensus pricing valuation technique | Level 3 | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		37	37
Banks/financial institutions
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		9,420	9,299
Banks/financial institutions | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		161	159
Banks/financial institutions | Discounted cash flow technique | Level 3 | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 161	$ 159
Banks/financial institutions | Discounted cash flow technique | Level 3 | Lower Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0067	0.0067
Banks/financial institutions | Discounted cash flow technique | Level 3 | Upper Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0188	0.0188
Banks/financial institutions | Discounted cash flow technique | Level 3 | Weighted Average | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0111	0.0113
Other corporate
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 29,142	$ 28,362
Other corporate | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		753	742
Other corporate | Discounted cash flow technique | Level 3 | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 753	$ 742
Other corporate | Discounted cash flow technique | Level 3 | Lower Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0066	0.0066
Other corporate | Discounted cash flow technique | Level 3 | Upper Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0295	0.0647
Other corporate | Discounted cash flow technique | Level 3 | Weighted Average | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Debt Securities, Available-for-Sale, Measurement Input	[2]	0.0187	0.0191

[1] Represents prices for securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques.

[2] Actual or equivalent credit spreads in basis points.